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I stumbled into a Celestron 8" SCT

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#76 Tenacious


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Posted 18 October 2016 - 02:39 PM

Thanks for the link.  I wonder how many others have gone that route to improve stability.


So, you're in the process of moving or building your dream home?  I hope to never move again.   It might be a while before you can pursue your ideas, but, all 4 of them make sense. 



Tom remade the mounting plate so it sits lower in the wedge.  This is something I've been wanting to do.  With the Super C8 it may take flipping the base to get it low enough.  If I were to build a new wedge from a clean sheet of paper, I'd probably not have the wedge extend so far from the center of the tripod.  I can see why Celestron (and later Meade) did this.  The CG of the entire system ends up more or less centered over the tripod, but I'd rather sacrifice this a bit for a little more stability from a shorter lever-arm.


Again, I'll bet a C8 mounted on a solid permanent pier (angled - no wedge) would be far more vibration resistant.  I've never had the opportunity to test this though.


Yes, Celestron and Meade needed to balance the mass above the tripod to prevent tipping while selling a product that could still be used in the greatest variety of latitude.  In truth, I took inspiration from an earlier Celestron design that had a bottom brace arrangement like mine.  I'm very pleased with the improved settle time that bottom brace provides and the system will still adjust to +/_ 15 degrees of my latitude (I'll never use this much).  Not bad.  I hear your argument about the wedge, but, I don't detect compliance there in my system (nor in the wedge plate, now  :grin: ).  I was shooting straight when I said most of the oscillation that remains appears to be in the fork arms.  I'll probably look deeper into this after the OTA has been serviced.  OTOH, I could stop here and simply enjoy acceptable damping times.


I never thought of flipping the base (so the controls are on the uphill side?).  Interesting idea.

Edited by Tenacious, 18 October 2016 - 02:45 PM.

#77 View2



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Posted 18 October 2016 - 02:52 PM

What on Earth do people do to these poor scopes? Do they just leave them outside for years? I cannot even imagine how you can get that degree of rust and corrosion on a telescope unless you really tried hard! So sad!

Well, you can start to resurrect it. Hats off to you!

Yes that's exactly what they do. I had a friend who had it 10 inch Meade cat and ended up using the tripod for satellite TV antenna mount

#78 Tom Stock

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Posted 18 October 2016 - 09:43 PM

If I remember correctly, the way I determined it was the base flexing was by pressing my thumb on the RA setting circle and edge of base. I then gave the fork a smack. You could feel the base ever so slightly pinching your finger against the setting circle as it rang like a tuning fork.


But, the LX-90 did it worse, mainly because it was a much heavier scope and fork.

Edited by Tom Stock, 18 October 2016 - 09:43 PM.

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#79 ssagerian


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Posted 10 November 2019 - 09:48 PM

Since you posted this, I started looking at Celestars on the net, too.  I'm getting that Celestron's model number scheme might have had some overlap or some ambiguity.  I suppose it doesn't matter too much provided there is a way forward with bringing it back and that it performs well.


It does appear that the hand controller and Dec. motor were options.   I did find a schematic for the hand controller, it's easy enough.

Can you post or email me that schematic for the hand controller? I just picked one of these scopes, its in fair condition. Thanks!


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